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.TH T_GETINFO 3NSL "Feb 17, 2023"
.SH NAME
t_getinfo \- get protocol-specific service information
.SH SYNOPSIS
.nf
#include <xti.h>



\fBint\fR \fBt_getinfo\fR(\fBint\fR \fIfd\fR, \fBstruct t_info *\fR\fIinfo\fR);
.fi

.SH DESCRIPTION
This routine is part of the \fBXTI\fR interfaces which evolved from the
\fBTLI\fR interfaces. \fBXTI\fR represents the future evolution of these
interfaces. However, \fBTLI\fR interfaces are supported for compatibility. When
using a \fBTLI\fR routine that has the same name as an \fBXTI\fR routine, the
\fBtiuser.h\fR header file must be used.  Refer to the  \fBTLI\fR
\fBCOMPATIBILITY\fR section for a description of differences between the two
interfaces.
.sp
.LP
This function returns the current characteristics of the underlying transport
protocol and/or transport connection associated with file descriptor \fIfd\fR.
The \fIinfo\fR pointer is used to return the same information returned by
\fBt_open\fR(3NSL), although not necessarily precisely the same values. This
function enables a transport user to access this information during any phase
of communication.
.sp
.LP
This argument points to a \fBt_info\fR structure which contains the following
members:
.sp
.in +2
.nf
t_scalar_t addr;     /*max size in octets of the transport protocol address*/
t_scalar_t options;  /*max number of bytes of protocol-specific options  */
t_scalar_t tsdu;     /*max size in octets of a transport service data unit */
t_scalar_t etsdu;    /*max size in octets of an expedited transport service*/
                     /*data unit (ETSDU) */
t_scalar_t connect;  /*max number of octets allowed on connection */
                     /*establishment functions */
t_scalar_t discon;   /*max number of octets of data allowed on t_snddis()  */
                     /*and t_rcvdis() functions */
t_scalar_t servtype; /*service type supported by the transport provider */
t_scalar_t flags;    /*other info about the transport provider */
.fi
.in -2

.sp
.LP
The values of the fields have the following meanings:
.sp
.ne 2
.na
\fB\fIaddr\fR\fR
.ad
.RS 12n
A value greater than zero indicates the maximum size of a transport protocol
address and a value of  \fBT_INVALID\fR (-2) specifies that the transport
provider does not provide user access to transport protocol addresses.
.RE

.sp
.ne 2
.na
\fB\fIoptions\fR\fR
.ad
.RS 12n
A value greater than zero indicates the maximum number of bytes of
protocol-specific options supported by the provider, and a value of
\fBT_INVALID\fR (-2) specifies that the transport provider does not support
user-settable options.
.RE

.sp
.ne 2
.na
\fB\fItsdu\fR\fR
.ad
.RS 12n
A value greater than zero specifies the maximum size in octets of a transport
service data unit (TSDU); a value of  \fBT_NULL\fR (zero) specifies that the
transport provider does not support the concept of TSDU, although it does
support the sending of a datastream with no logical boundaries preserved across
a connection; a value of  \fBT_INFINITE\fR (-1) specifies that there is no
limit on the size in octets of a TSDU; and a value of  \fBT_INVALID\fR (-2)
specifies that the transfer of normal data is not supported by the transport
provider.
.RE

.sp
.ne 2
.na
\fB\fIetsdu\fR\fR
.ad
.RS 12n
A value greater than zero specifies the maximum size in octets of an expedited
transport service data unit (ETSDU); a value of  \fBT_NULL\fR (zero) specifies
that the transport provider does not support the concept of ETSDU, although it
does support the sending of an expedited data stream with no logical boundaries
preserved across a connection; a value of  \fBT_INFINITE\fR (-1) specifies that
there is no limit on the size (in octets) of an ETSDU; and a value of
\fBT_INVALID\fR (-2) specifies that the transfer of expedited data is not
supported by the transport provider. Note that the semantics of expedited data
may be quite different for different transport providers.
.RE

.sp
.ne 2
.na
\fB\fIconnect\fR\fR
.ad
.RS 12n
A value greater than zero specifies the maximum number of octets that may be
associated with connection establishment functions and a value of
\fBT_INVALID\fR (-2) specifies that  the transport provider does not allow data
to be sent with connection establishment functions.
.RE

.sp
.ne 2
.na
\fB\fIdiscon\fR\fR
.ad
.RS 12n
If the  \fBT_ORDRELDATA\fR bit in flags is clear, a value greater than zero
specifies the maximum number of octets that may be associated with the
\fBt_snddis\fR(3NSL) and \fBt_rcvdis\fR(3NSL) functions, and a value of
\fBT_INVALID\fR (-2) specifies that  the transport provider does not allow data
to be sent with the abortive release functions. If the  \fBT_ORDRELDATA\fR bit
is set in flags, a value greater than zero specifies the maximum number of
octets that may be associated with the  \fBt_sndreldata()\fR,
\fBt_rcvreldata()\fR, \fBt_snddis\fR(3NSL) and  \fBt_rcvdis\fR(3NSL) functions.
.RE

.sp
.ne 2
.na
\fB\fIservtype\fR\fR
.ad
.RS 12n
This field specifies the service type supported by the transport provider, as
described below.
.RE

.sp
.ne 2
.na
\fB\fIflags\fR\fR
.ad
.RS 12n
This is a bit field used to specify other information about the  communications
provider.  If the  \fBT_ORDRELDATA\fR bit is set, the communications provider
supports sending user data with an orderly release. If the  \fBT_SENDZERO\fR
bit is set in flags, this indicates that the underlying transport provider
supports the sending of zero-length TSDUs.
.RE

.sp
.LP
If a transport user is concerned with protocol independence, the above sizes
may be accessed to determine how large the buffers must be to hold each piece
of information.  Alternatively, the \fBt_alloc\fR(3NSL) function may be used to
allocate these buffers. An error will result if a transport user exceeds the
allowed data size on any function. The value of each field may change as a
result of protocol option negotiation during connection establishment (the
\fBt_optmgmt\fR(3NSL) call has no effect on the values returned by
\fBt_getinfo()\fR\|). These values will only change from the values presented
to \fBt_open\fR(3NSL) after the endpoint enters the  \fBT_DATAXFER\fR state.
.sp
.LP
The \fIservtype\fR field of \fIinfo\fR specifies one of the following values on
return:
.sp
.ne 2
.na
\fB\fBT_COTS\fR \fR
.ad
.RS 15n
The transport provider supports a connection-mode service but does not support
the optional orderly release facility.
.RE

.sp
.ne 2
.na
\fB\fBT_COTS_ORD\fR \fR
.ad
.RS 15n
The transport provider supports a connection-mode service with the optional
orderly release facility.
.RE

.sp
.ne 2
.na
\fB\fBT_CLTS\fR \fR
.ad
.RS 15n
The transport provider supports a connectionless-mode service. For this service
type, \fBt_open\fR(3NSL) will return  \fBT_INVALID\fR (-1) for \fIetsdu\fR,
\fIconnect\fR and \fIdiscon\fR.
.RE

.SH RETURN VALUES
Upon successful completion, a value of  \fB0\fR is returned.  Otherwise, a
value of  -1 is returned and \fBt_errno\fR is set to indicate an error.
.SH VALID STATES
ALL - apart from \fBT_UNINIT\fR.
.SH ERRORS
On failure, \fBt_errno\fR is set to one of the following:
.sp
.ne 2
.na
\fB\fBTBADF\fR\fR
.ad
.RS 11n
The specified file descriptor does not refer to a transport endpoint.
.RE

.sp
.ne 2
.na
\fB\fBTPROTO\fR\fR
.ad
.RS 11n
This error indicates that a communication problem has been detected between XTI
and the transport provider for which there is no other suitable XTI error
\fB(t_errno)\fR.
.RE

.sp
.ne 2
.na
\fB\fBTSYSERR\fR\fR
.ad
.RS 11n
A system error has occurred during execution of this function.
.RE

.SH TLI COMPATIBILITY
The \fBXTI\fR and \fBTLI\fR interface definitions have common names but use
different header files. This, and other semantic differences between the two
interfaces are described in the subsections below.
.SS "Interface Header"
The \fBXTI\fR interfaces use the header file, \fBxti.h\fR. \fBTLI\fR interfaces
should \fInot\fR use this header.  They should use the header:
.sp
.in +2
.nf
#include <tiuser.h>
.fi
.in -2

.SS "Error Description Values"
The \fBt_errno\fR value \fBTPROTO\fR can be set by the \fBXTI\fR interface but
not by the \fBTLI\fR interface.
.SS "The t_info Structure"
For \fBTLI\fR, the \fBt_info\fR structure referenced by \fIinfo\fR lacks the
following structure member:
.sp
.in +2
.nf
t_scalar_t flags;    /* other info about the transport provider */
.fi
.in -2

.sp
.LP
This member was added to \fBstruct\fR \fBt_info\fR in the \fBXTI\fR interfaces.
.sp
.LP
When a value of -1 is observed as the return value in various \fBt_info\fR
structure members, it signifies that the transport provider can handle an
infinite length buffer for a corresponding attribute, such as address data,
option data, \fBTSDU\fR (octet size), \fBETSDU\fR (octet size), connection
data, and disconnection data. The corresponding structure members are
\fBaddr\fR, \fBoptions\fR, \fBtsdu\fR, \fBestdu\fR, \fBconnect\fR, and
\fBdiscon\fR, respectively.
.SH ATTRIBUTES
See \fBattributes\fR(7)  for descriptions of the following attributes:
.sp

.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
MT Level	Safe
.TE

.SH SEE ALSO
.BR t_alloc (3NSL),
.BR t_open (3NSL),
.BR t_optmgmt (3NSL),
.BR t_rcvdis (3NSL),
.BR t_snddis (3NSL),
.BR attributes (7)
